Halogenated rubbers such as chlorosulfonated polyethylene and chlorinated polyethylene require activators to aid in curing the rubber and to stabilize the cured rubber. In the case of chlorosulfonated polyethylene and chlorinated polyethylene rubbers, metal oxides, and hydroxides of lead, cadmium, magnesium, calcium and barium have been used as activators and stabilizers. Toxicity concerns have decreased the use of barium, cadmium and lead which leaves calcium and magnesium as the most common stabilizer. These are known to be moisture sensitive and cause water absorption and are very unsatisfactory for producing vulcanizates for tank linings.
In the case of polychloroprene rubber, oxides of zinc and magnesium and lead are commonly used to activate the cure and stabilize the vulcanizate. Zinc is known to produce moisture sensitivity, resulting in water absorption. In cases where water immersion is needed, lead oxides are preferred in place of zinc oxide and magnesium oxide. Landfill requirements require a limited lead content in acidic leachate tests and lead stabilized polymers are recognized as a disposal problem. Consequently, a need exists for an improved curative-stabilizer for the halogenated rubber vulcanizates other than lead salts.